The Tritone: Understanding the Devil's Interval in Music

The tritone is one of the most fascinating and controversial intervals in music theory. Spanning three whole tones (hence the name "tritone"), this interval has been called the "devil's interval" due to its historically dissonant sound and association with forbidden music.

What is a Tritone?

A tritone is an interval of an augmented fourth (A4) or diminished fifth (d5). On the piano, it's the distance between C and F# (augmented fourth) or C and Gb (diminished fifth). These two spellings represent the same sonic interval but function differently in musical contexts.

Technical Construction

The tritone divides the octave exactly in half:

• Augmented fourth: 6 half-steps up from the root
• Diminished fifth: 6 half-steps down from the octave

Historical Context

In medieval times, the tritone was avoided in sacred music and called "diabolus in musica" (the devil in music). Composers believed its dissonance could summon evil spirits. However, by the Romantic era, composers like Wagner embraced its tension for dramatic effect.

Musical Applications

Classical Music

The tritone appears prominently in:

• Wagner's "Tristan und Isolde" prelude
• Liszt's "Dante Sonata"
• Stravinsky's "Rite of Spring"

Jazz and Blues

Jazz musicians use tritones for:

• Dominant 7th chords (the 3rd and b7th form a tritone)
• Tritone substitutions (replacing a V7 chord with another dominant 7th a tritone away)
• Blues licks and riffs

Rock and Metal

The tritone creates the signature sound of:

• Black Sabbath's "Black Sabbath" (main riff)
• Metallica's "Enter Sandman" (verse riff)
• Jim Hendrix's "Purple Haze" (opening chord)

Practical Exercises

Level 1: Identification

Play these tritone pairs on your instrument:

• C to F#
• G to C#
• D to G#

Level 2: Chord Construction

Build dominant 7th chords and identify the tritone between 3rd and b7th:

• G7 (B-F)
• C7 (E-Bb)
• F7 (A-Eb)

Level 3: Tritone Substitution

Practice substituting V7 chords:

• Original: D7 - G7 - C
• Substituted: D7 - Db7 - C

Ear Training Tips

Recognize tritones by their distinctive, unstable quality. Common associations include:

• The "Simpsons" theme opening
• "Maria" from West Side Story ("Ma-ri-a" spans a tritone)
• Police siren intervals

Conclusion

While historically feared, the tritone has become an essential tool for creating tension and color in modern music. Mastering this interval will significantly expand your harmonic palette across all genres.